Solar Inverter and Combiner Box Inspection

Inspection checklist for central or string solar inverters and combiner boxes, focused on fault codes, fuse condition and sizing, moisture intrusion, grounding continuity, and fire/electrical safety compliance.

Inspection Details and Safe Work Controls

• Equipment identification recorded
  Record inverter ID, combiner box ID, location, and asset tag.
• Inspection date and time recorded
  Document when the inspection was performed.
• Lockout-tagout applied before opening enclosure
  Verify the equipment was isolated and controlled before access to internal components.
• PPE appropriate for electrical work used
  Confirm required PPE was used based on site hazard assessment.

Inverter Status and Fault Codes

• Inverter display shows normal operating status
  Verify the inverter is not in shutdown, derate, or alarm state.
• Active fault codes recorded
  Record all active fault codes, alarms, and event messages shown on the inverter or monitoring interface.
• Historical fault log reviewed
  Confirm recent fault history was reviewed for recurring issues, nuisance trips, or thermal events.
• Cooling fans, vents, and heat sinks unobstructed
  Check that airflow paths are clear and no debris is blocking cooling components.
• Signs of overheating or thermal damage present
  Inspect for discoloration, melted insulation, odor, or heat damage on the enclosure or components.

Combiner Box Fuses, Wiring, and Terminations

• Fuses present and intact
  Verify all required fuses are installed and not open, cracked, or heat damaged.
• Fuse size matches inverter and string design
  Confirm fuse amp rating matches the approved design and equipment nameplate requirements.
• Terminations are secure and properly torqued
  Check for loose lugs, damaged conductors, or signs of overheating at terminations.
• Conductor insulation and routing are in good condition
  Verify conductors are not nicked, pinched, abraded, or routed in a way that creates strain or abrasion.
• Evidence of arcing or burn marks present
  Inspect for soot, pitting, melted plastic, or other arc-fault indicators inside the combiner box.

Moisture, Corrosion, and Enclosure Condition

• Enclosure is dry and free of moisture intrusion
  Check for standing water, condensation, dampness, or water staining inside the enclosure.
• Gaskets, seals, and conduit entries intact
  Verify door seals, glands, and conduit fittings are intact and maintain enclosure integrity.
• Corrosion or contamination present
  Inspect for rust, white powder, dirt buildup, insect intrusion, or other contamination on internal components.
• Enclosure door closes and latches properly
  Confirm the enclosure can be fully closed and secured to maintain weather resistance and access control.

Grounding, Bonding, and Final Corrective Actions

• Grounding and bonding conductors secure and continuous
  Verify grounding/bonding conductors are intact, properly terminated, and free of damage.
• Ground continuity verified with test result
  Record measured continuity or resistance value for the grounding path.
• Deficiencies documented with corrective action
  List any non-conformances, immediate hazards, and recommended corrective actions.
• Escalation to maintenance or AHJ required
  Select whether the issue requires escalation.